The groups, mostly from the Northwest, will file an appeal and a motion to stay the ban within the next week or two, said Corinne Simon of CropLife America, a pesticide trade association based in Washington, D.C.

The action will be filed in the 9th U.S. Circuit Court of Appeals in San Francisco, she said.

On Jan. 22, U.S. District Judge John Coughenour of Seattle banned ground spraying of 38 pesticides within 60 feet of streams and aerial spraying within 300 feet of streams.

Heather Hansen, executive director of Washington Friends of Farms and Forests in Olympia, said she hopes the decision can be stayed in time to allow farmers to keep using the pesticides on this year's crops.

"The basis for the stay is that there will be significant impact on Pacific Northwest growers," Simon said, citing a U.S. Department of Agriculture study last August that estimated the economic impact to Washington farmers alone could be $31 million to $495 million annually.

The appeal also will argue that Coughenour did not identify actual harm to salmon on which to base the ban, Simon said.

"It's not up to the defendants to prove something is safe. It's up to the plaintiffs to prove harm. Our position is that wasn't done," she said.

Patti Goldman, attorney for the Seattle-based Washington Toxics Coalition, said the groups faced an uphill battle to get a stay.

The coalition and three other groups sued the Environmental Protection Agency for violating the Endangered Species Act by failing to consult with the National Oceanic and Atmospheric Administration Fisheries in its review of 54 pesticides.

Coughenour ruled in their favor in 2002 and issued the ban last month.

Goldman said it probably would be several weeks to a month, after the motion is filed, before a panel of three judges at the appeals court would rule on it.